package cn.djun.news.interceptor;

import cn.djun.news.entity.User;
import cn.djun.news.service.UserService;
import cn.djun.news.util.PassToken;
import cn.djun.news.util.UserLoginToken;
import com.auth0.jwt.JWT;
import com.auth0.jwt.JWTVerifier;
import com.auth0.jwt.algorithms.Algorithm;
import com.auth0.jwt.exceptions.JWTDecodeException;
import com.auth0.jwt.exceptions.JWTVerificationException;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.lang.reflect.Method;

/**
 * @author djun
 * @classname AuthenticationInterceptor
 * @description
 * @date 2020/11/23 10:12
 * @email 3170495286@qq.com
 */
public class AuthenticationInterceptor extends HandlerInterceptorAdapter {
    @Autowired
    private UserService userService;

    /**
     * 执行目标方法之前拦截验证Token。
     *
     * @param httpServletRequest * @param httpServletResponse
     * @param object             * @return
     * @throws Exception
     */
    @Override
    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse
            httpServletResponse, Object object)
            throws Exception {
        // 从 http 请求头中取出 token
        String token = httpServletRequest.getHeader("token");
        // 如果不是映射到方法直接通过
        if (!(object instanceof HandlerMethod)) {
            return true;
        }
        HandlerMethod handlerMethod = (HandlerMethod) object;
        Method method = handlerMethod.getMethod();
        //检查是否有PassToken注释，有则跳过认证
        if (method.isAnnotationPresent(PassToken.class)) {
            PassToken passToken = method.getAnnotation(PassToken.class);
            if (passToken.required()) {
                return true;
            }
        }
        //检查有没有需要用户权限的注解
        if (method.isAnnotationPresent(UserLoginToken.class)) {
            UserLoginToken userLoginToken = method.getAnnotation(UserLoginToken.class);
            if (userLoginToken.required()) {
             // 执行认证
                if (token == null) {
                    throw new RuntimeException("无token，请检查是否登录");
                }
                //获取token中的user的id
                int id;
                try {
                    id = Integer.parseInt(JWT.decode(token).getAudience().get(0));
                } catch (JWTDecodeException j) {
                    throw new RuntimeException("401");
                }
                User user = userService.getUserById(id);
                if (user == null) {
                    throw new RuntimeException("用户不存在，请重新登录");
                }
                // 验证token
                JWTVerifier jwtVerifier = JWT.require(Algorithm.HMAC256(user.getPassword())).build();
                try {
                    jwtVerifier.verify(token);
                } catch (JWTVerificationException e) {
                    throw new RuntimeException("401");
                }
            } else {
                throw new RuntimeException("无认证方法无法访问");
            }
            return true;
        }
        return true;

    }
}
